Good (cheap) flash memory chips?

Why not just use an off the shelf IDE Flash drive, or a CF card?. You will be unlikely to beat the prices you can get these for, unless you are buying in 10000 off quantities, and most of the work has already been done... You make no mention of the actual capacities required from the unit. For smaller capacities look at FRAM, but because this only comes in 'bytewide' or serial forms, you would need to provide the IDE interface. Has probably the best cycle life, and data retention around.

Best Wishes

I'm hoping to get into the 20GB range for the drive, something not currently offered in comercial drives. Stacking many smaller chips will probably be cheaper thant trying to go with a few large ones, no? I'm hoping someone has already done a project like this and can point me to the chip they used, as too much trial and error is budget prohibitive.

Thanks, Mike

Maybe you could hook a bunch of CF cards to a RAID controller....!

many

scale.

That's already been done. All you do is buy the adapter to fit a Compact Flash card to an IDE cable. It's just a PC board with a socket for the IDE cable, and a socket for the CF card. No power, no nothing, and cheap, too, unless you buy it with the bracket to nount it in your FDD enclosure. I think it's Addonics that makes one to fit into the hole where your 3.5" floppy goes.

You can insert a CF card for 32MB --> 128MB --> 512MB or all the way up to 4GB or 8GB, or else use a microdrive which is CF type 2, thicker card. It's bootable, too. See this one:

Also you can buy an adapter to put a CF card into the PC slot in your laptop. The adapter costs less than $15, sometimes less than $10. Works just like another disk drive. You can also get an adapter to connect the PCMCIA card to an IDE cable, just like above.

Wow, 2GB microdrives are under $70! They'll be coming out with a 20GB soon. Looks like a 6GB is a couple hundred. But if you must have flash, a 1GB is well under a hundred.

rd

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CF cards have some intelligence in them that writes over a new spot instead of rewriting over the same spot every time, and thus 'wearing out' or using up the write cycles. If you can do that with just the basic chips, then go for it. I would use the CF cards, they're so much simpler and cheaper.

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prohibitive.

I thought mose RAIDs are SCSI. Not only that, but what will it get you? CF cards don't 'crash' like a hard disk. Just make sure they're backed up often.

Probably not cheap, though...

MemTech do IDE flash drives to 13GB, and in a larger format, flash drives up to 60GB. Look at:

They use capacitors, to maintain the supply long enough to guarantee a write completes when power is removed, which allows them to use a cache RAM, to reduce the number of memory cycles involved. In common with most manufacturers here, they also 'walk' the sectors used, to avoid repeated I/O on a single location, using up the memory life too quickly (they call this 'active remap'. They also implement error recovery algorithms in the memory. There is a lot of work in making a drive like this. You need the IDE interface (simple), cache controller (relatively simple), systems to guarantee write completion (power backup), algorithms to get away from continuously using one sector, the hardware to implement these, and then ECC handling. You are looking at probably a years work for a couple of people from a 'standing start', if you have not got experience in this area...

Best Wishes

That's cool, does all sorts of neat things, like it probably has a cache of regular RAM to speed it up. If you need that. But like you say,

when you compare it to a 1GB compact flash card and adapter, all for under a hundred.

Ah, perfect! Just what I was trying to build. Thanks a heap.

Mike